CN215027407U - Processing system of nitrogen trifluoride electrolysis trough cathode tail gas - Google Patents
Processing system of nitrogen trifluoride electrolysis trough cathode tail gas Download PDFInfo
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- CN215027407U CN215027407U CN202023127780.6U CN202023127780U CN215027407U CN 215027407 U CN215027407 U CN 215027407U CN 202023127780 U CN202023127780 U CN 202023127780U CN 215027407 U CN215027407 U CN 215027407U
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Abstract
The utility model discloses a nitrogen trifluoride electrolysis trough cathode tail gas's processing system, include: a main cathode gas pipeline of the electrolytic cell, an HF condenser, an HF absorption device and an HF recovery tank; cathode chambers of all the electrolytic cells are connected to a cathode gas main pipeline of the electrolytic cells through a cathode tail gas transmission pipeline; the HF condenser is provided with a gas inlet to be condensed, a condensed liquid outlet, a condensed gas outlet, a condensed medium inlet and a condensed medium outlet; the gas inlet to be condensed is connected to the cathode gas main pipeline of the electrolytic cell, the condensed liquid outlet is connected to an HF recovery tank through an HF recovery pipeline connected with a liquid discharge valve, and the condensed gas outlet is connected to an HF absorption device through a gas supply pipeline; the HF absorber includes a tertiary absorber assembly. The utility model discloses can realize HF's collection and absorption among the cathode tail gas, realize the HF up to standard emission among the electrolysis trough cathode tail gas.
Description
Technical Field
The utility model relates to a nitrogen trifluoride electrolysis trough cathode tail gas handles technical field, especially relates to a nitrogen trifluoride electrolysis trough cathode tail gas's processing system.
Background
The chemical formula of nitrogen trifluoride is NF3It is a colorless, odorless and stable gas at normal temperature, and is a strong oxidant. Nitrogen trifluoride is an excellent plasma etching gas in the microelectronic industry, has higher etching rate and selectivity for etching silicon and silicon nitride compared with carbon tetrafluoride and mixed gas of carbon tetrafluoride and oxygen, has no pollution to the surface, has excellent etching rate and selectivity particularly in the etching of integrated circuit materials with the thickness of less than 1.5um, does not leave any residue on the surface of an etched object, and is a very good cleaning agent. With the development of nanotechnology and the large-scale development of technology in the electronics industry, the demand for it will increase.
At present, the domestic treatment mode of chemical neutralization reaction is mainly adopted for waste gas generated by nitrogen trifluoride electrolysis. The problem of whether the HF in the cathode tail gas is discharged after reaching the standard or not after being purified is also solved simultaneously in the HF treatment in the cathode tail gas generated by the electrolysis of nitrogen trifluoride.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model provides a nitrogen trifluoride electrolysis trough cathode tail gas's processing system can realize HF's collection and absorption in the cathode tail gas, realizes the HF up to standard emission in the electrolysis trough cathode tail gas.
In order to solve the technical problem, the utility model discloses a so realize.
A system for treating cathode tail gas of a nitrogen trifluoride electrolyzer, comprising: a main cathode gas pipeline of the electrolytic cell, an HF condenser, an HF absorption device and an HF recovery tank;
cathode chambers of all the electrolytic cells are connected to a cathode gas main pipeline of the electrolytic cells through a cathode tail gas transmission pipeline;
the HF condenser is provided with a gas inlet to be condensed, a condensed liquid outlet, a condensed gas outlet, a condensed medium inlet and a condensed medium outlet; the gas inlet to be condensed is connected to the cathode gas main pipeline of the electrolytic cell, the condensed liquid outlet is connected to an HF recovery tank through an HF recovery pipeline connected with a liquid discharge valve, and the condensed gas outlet is connected to an HF absorption device through a gas supply pipeline;
the HF absorber comprises a three-stage absorber tower assembly; each level of absorption tower assembly comprises a spray absorption tower and an acid tank: an acid liquor outlet of the acid tank is connected with a circulating liquid adding port of the first-stage acid tank and an absorption liquid inlet of the spraying absorption tower through an acid liquor circulating pipeline with a circulating pump; an acid liquor outlet at the bottom of the spraying absorption tower is connected to the acid tank through an acid liquor recovery pipeline; the top of the spray absorption tower is connected to the bottom of the next stage of spray absorption tower through an HF discharge pipeline; the acid liquor outlet of the first-stage acid tank is connected with the absorption liquid inlet of the first-stage spray absorption tower only through an acid liquor circulation pipeline with a circulating pump, the acid liquor outlet of the first-stage acid tank is used as a finished acid discharge port, the circulation liquid adding port of the third-stage acid tank is connected with external pure water adding equipment, and the HF discharge pipeline of the third-stage spray absorption tower is connected into the external discharge tower.
Preferably, the cathode tail gas transmission pipeline, the acid liquor circulation pipeline, the HF discharge pipeline and the acid liquor recovery pipeline are all provided with valves.
Preferably, the condensing medium passed into the HF condenser is cold nitrogen.
Preferably, the gas inlet to be condensed is arranged at the lower part of the HF condenser, the condensed liquid outlet is arranged at the bottom of the HF condenser, and the condensed gas outlet is arranged at the top of the HF condenser.
Preferably, the number of the HF condensers is 2, and the HF condensers are connected in parallel; and a valve is arranged on a pipeline connected with the gas inlet to be condensed, the condensed liquid outlet, the condensed gas outlet, the condensed medium inlet and the condensed medium outlet of each HF condenser.
Preferably, the nominal diameter of the cathode gas main pipeline of the electrolytic cell is 150mm, and the pipeline is made of carbon steel pipe lined with fluorine.
Preferably, the condensation temperature of the HF condenser is-45 +/-15 ℃, and the pressure of the HF condenser is normal pressure.
Preferably, a temperature sensor and a heating device are arranged in the spray absorption tower, and the temperature of the spray absorption tower is kept at 20 +/-5 ℃; the pressure of the spray absorption tower is in a normal pressure state.
Has the advantages that:
(1) the components of the cathode tail gas of the electrolytic cell mainly comprise hydrogen, hydrogen fluoride and nitrogen, and HF in the cathode tail gas generated by the electrolytic cell is completely collected and absorbed by using a condenser and an HF absorption device under the condition of continuously generating nitrogen trifluoride, so that the standard emission of HF in the cathode tail gas of the electrolytic cell can be realized.
(2) Through the addition of condenser, with most HF condensation for HF liquid and retrieve in the tail gas, subsequent HF absorbing device only needs to adopt 3 grades of absorption towers can realize almost whole HF's recovery, has both guaranteed that tail gas emission up to standard accords with the environmental protection requirement, can reduce certain cost again.
Drawings
FIG. 1 is a block diagram showing the components of a system for treating tail gas from the cathode of a nitrogen trifluoride electrolyzer.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings by way of examples.
The utility model provides a nitrogen trifluoride electrolysis trough cathode tail gas's processing system, as shown in figure 1, it includes electrolysis trough cathode gas trunk line, HF condenser, HF absorbing device, HF recovery tank.
Cathode chambers of all the electrolytic cells are connected to a cathode gas main pipeline of the electrolytic cells through a cathode tail gas transmission pipeline. The nominal diameter of the cathode gas main pipeline of the electrolytic cell is preferably 150mm, and the pipeline is made of carbon steel pipe lined with fluorine, so that the corrosion of the cathode gas to the pipeline is prevented. A valve can be arranged on the cathode tail gas transmission pipeline to control which electrolytic cells participate in the tail gas treatment of the system.
The HF condenser has a gas inlet to be condensed, a condensed liquid outlet, a condensed gas outlet, a condensing medium inlet and a condensing medium outlet. The gas inlet to be condensed is arranged at the lower part of the HF condenser, the condensed liquid outlet is arranged at the bottom of the HF condenser, and the condensed gas outlet is arranged at the top of the HF condenser. The condensing medium inlet and the condensing medium outlet are respectively arranged at the lower part and the upper part of the HF condenser, the condensing medium is cold nitrogen and flows from bottom to top, and thus the condensing temperature of the HF condenser is controlled to be minus 45 +/-15 ℃. The condenser was at normal atmospheric pressure.
And a gas inlet to be condensed is connected to the cathode gas main pipeline of the electrolytic cell, a condensed liquid outlet is connected to an HF recovery tank through an HF recovery pipeline connected with a liquid discharge valve, and a condensed gas outlet is connected to an HF absorption device through an air supply pipeline.
In this embodiment, there are 2 HF condensers, one being a main device and the other being a standby device, which are connected in parallel. And a valve is arranged on a pipeline connected with the gas inlet to be condensed, the condensed liquid outlet, the condensed gas outlet, the condensed medium inlet and the condensed medium outlet of each HF condenser. The switching of the currently used equipment is realized through valve switch control.
The HF absorber includes a three stage absorber assembly. Most of HF is condensed into liquid by the condenser for recovery, so that the condensed cathode gas only contains a small amount of HF gas, and most of HF can be absorbed by only three stages of absorption towers, so that finished acid is recovered.
As shown in fig. 1, each stage of absorption tower assembly comprises a spray absorption tower and an acid tank: an acid liquor outlet of the acid tank is connected with a circulating liquid adding port of the first-stage acid tank and an absorption liquid inlet of the spraying absorption tower through an acid liquor circulating pipeline with a circulating pump; an acid liquor outlet at the bottom of the spraying absorption tower is connected to the acid tank through an acid liquor recovery pipeline; the top of the spray absorption tower is connected to a gas inlet at the bottom of the next stage of spray absorption tower through an HF discharge pipeline; the acid liquor outlet of the first-stage acid tank is connected with the absorption liquid inlet of the spraying absorption tower through an acid liquor circulation pipeline with a circulating pump, the acid liquor outlet of the first-stage acid tank is used as a finished acid discharge port, the circulation liquid adding port of the third-stage acid tank is connected with pure water adding equipment, and the HF discharge pipeline of the third-stage spraying absorption tower is connected into an external discharge tower. Valves can be arranged in the acid liquor circulating pipeline, the HF discharging pipeline and the acid liquor circulating pipeline so as to realize closing during equipment maintenance.
A temperature sensor and a heating device are arranged in the spray absorption tower, and the temperature of the spray absorption tower is 20 +/-5 ℃; the pressure of the spray absorption tower is in a normal pressure state.
The working process of the processing system is as follows:
and the cathode tail gas generated by the electrolytic cell is conveyed to an HF condenser for condensation treatment by a cathode gas main pipeline of the electrolytic cell.
The HF condenser carries out deep condensation on the sent cathode tail gas, most of HF gas in the cathode tail gas is condensed into HF liquid, and the HF liquid is discharged to an HF recovery tank from a liquid discharge valve at the lower part of the HF condenser periodically; and the cathode tail gas is condensed by a condenser and then sent to an HF absorption device for purification treatment.
And the condensed cathode tail gas continuously enters a primary spray absorption tower, a secondary spray absorption tower and a tertiary spray absorption tower in the HF absorption device. Spraying acid liquor generated by the absorption tower into the acid tank of the stage; and (3) pumping pure water into the tertiary acid tank, pumping the circulating water in the tertiary acid tank into the secondary acid tank in sequence by using a circulating pump, pumping the circulating water in the secondary acid tank into the primary acid tank to ensure that the pure water fully absorbs HF in the cathode gas until the primary acid tank discharges the finished acid with the concentration meeting the requirement through a finished acid discharge port. Circulating water of each stage of acid tank is further pumped into the spray absorption tower of the stage for further absorbing HF.
The utility model discloses among the processing system, electrolysis trough cathode tail gas composition is mainly hydrogen, hydrogen fluoride and nitrogen gas, under the condition that produces nitrogen trifluoride in succession, utilizes the HF of condenser and HF absorbing device in with the cathode tail gas of electrolysis trough production all to collect and absorb, can realize the HF discharge to reach standard in the electrolysis trough cathode tail gas.
The treatment system of the cathode tail gas of the electrolytic cell can reduce the content of HF in the tail gas to be below 3ppm, simultaneously can recover more than 50% of anhydrous HF for recycling to production, and the rest 50% of anhydrous HF is prepared into hydrofluoric acid to be sold as a byproduct. The tail gas is ensured to be discharged up to the standard, the environmental protection requirement is met, and certain cost can be reduced.
The above embodiments only describe the design principle of the present invention, and the shapes and names of the components in the description may be different without limitation. Therefore, a person skilled in the art of the present invention can modify or substitute the technical solutions described in the foregoing embodiments; the modifications and substitutions do not depart from the spirit and technical scope of the present invention, and shall all fall within the scope of the present invention.
Claims (8)
1. A system for treating tail gas of a cathode of a nitrogen trifluoride electrolysis cell, which is characterized by comprising: a main cathode gas pipeline of the electrolytic cell, an HF condenser, an HF absorption device and an HF recovery tank;
cathode chambers of all the electrolytic cells are connected to a cathode gas main pipeline of the electrolytic cells through a cathode tail gas transmission pipeline;
the HF condenser is provided with a gas inlet to be condensed, a condensed liquid outlet, a condensed gas outlet, a condensed medium inlet and a condensed medium outlet; the gas inlet to be condensed is connected to the cathode gas main pipeline of the electrolytic cell, the condensed liquid outlet is connected to an HF recovery tank through an HF recovery pipeline connected with a liquid discharge valve, and the condensed gas outlet is connected to an HF absorption device through a gas supply pipeline;
the HF absorber comprises a three-stage absorber tower assembly; each level of absorption tower assembly comprises a spray absorption tower and an acid tank: an acid liquor outlet of the acid tank is connected with a circulating liquid adding port of the first-stage acid tank and an absorption liquid inlet of the spraying absorption tower through an acid liquor circulating pipeline with a circulating pump; an acid liquor outlet at the bottom of the spraying absorption tower is connected to the acid tank through an acid liquor recovery pipeline; the top of the spray absorption tower is connected to the bottom of the next stage of spray absorption tower through an HF discharge pipeline; the acid liquor outlet of the first-stage acid tank is connected with the absorption liquid inlet of the first-stage spray absorption tower only through an acid liquor circulation pipeline with a circulating pump, the acid liquor outlet of the first-stage acid tank is used as a finished acid discharge port, the circulation liquid adding port of the third-stage acid tank is connected with external pure water adding equipment, and the HF discharge pipeline of the third-stage spray absorption tower is connected into the external discharge tower.
2. The system of claim 1, wherein the cathode tail gas transfer line, the acid liquor circulation line, the HF discharge line, and the acid liquor recovery line are provided with valves.
3. The system of claim 1, wherein the condensing medium passed into the HF condenser is cold nitrogen.
4. The system of claim 1, wherein the gas inlet to be condensed is disposed at a lower portion of the HF condenser, the condensed liquid outlet is disposed at a bottom portion of the HF condenser, and the condensed gas outlet is disposed at a top portion of the HF condenser.
5. The system of claim 1, wherein the HF condensers are 2, connected in parallel; and a valve is arranged on a pipeline connected with the gas inlet to be condensed, the condensed liquid outlet, the condensed gas outlet, the condensed medium inlet and the condensed medium outlet of each HF condenser.
6. The system of claim 1, wherein the nominal diameter of the main cathode gas conduit of the electrolytic cell is 150mm, and the conduit is made of carbon steel tube lined with fluorine.
7. The system of claim 1, wherein the HF condenser has a condensation temperature of-45 ± 15 ℃ and a condenser pressure of atmospheric pressure.
8. The system of claim 1, wherein a temperature sensor and a heating device are arranged in the spray absorption tower, and the temperature of the spray absorption tower is kept at 20 +/-5 ℃; the pressure of the spray absorption tower is in a normal pressure state.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202023127780.6U CN215027407U (en) | 2020-12-22 | 2020-12-22 | Processing system of nitrogen trifluoride electrolysis trough cathode tail gas |
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| CN202023127780.6U CN215027407U (en) | 2020-12-22 | 2020-12-22 | Processing system of nitrogen trifluoride electrolysis trough cathode tail gas |
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| CN202023127780.6U Active CN215027407U (en) | 2020-12-22 | 2020-12-22 | Processing system of nitrogen trifluoride electrolysis trough cathode tail gas |
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Address after: 057550 No. five Weir Road, chemical industry gathering area, Feixiang District, Handan, Hebei, 1 Patentee after: China shipbuilding (Handan) Perry Special Gas Co.,Ltd. Address before: No.1 Weiwu Road, chemical industry gathering area, Feixiang County, Handan City, Hebei Province Patentee before: PERIC SPECIAL GASES Co.,Ltd. |
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